Estimation of planes of a rock mass in a gallery wall from point cloud data based on MD PSO

Matsuura, Yuto*; Hayano, Akira; Itakura, Kenichi*; Suzuki, Yukinori*

Applied Soft Computing, 84, p.105737_1 - 105737_9, 2019/11

https://doi.org/10.1016/j.asoc.2019.105737

LiDAR (laser imaging detection and ranging) has been developed to obtain a high-resolution point cloud data indicating the detailed 3D shapes of an object. To identify discontinuities in a rock mass of a tunnel gallery wall, it is necessary to approximate the rock mass surface with small planes. Normal vectors of the planes are important to identify discontinuities. We developed an algorithm for estimation of planes based on multi-dimensional particle swarm optimization (MD PSO) from point cloud data. Point cloud data were segmented into bounding boxes and grouped into clusters by MD PSO. Planes were estimated using the least squares method for point cloud data in the respective clusters. The newly developed MD PSO algorithm was evaluated using point cloud data obtained from a gallery wall. Evaluation was carried out in comparison with the previous developed variable-box segmentation (VBS) algorithm. The MD PSO-based algorithm showed a 7% higher accuracy than that of the VBS algorithm.

STRAD project for systematic treatments of radioactive liquid wastes generated in nuclear facilities

Watanabe, So; Ogi, Hiromichi*; Arai, Yoichi; Aihara, Haruka; Takahatake, Yoko; Shibata, Atsuhiro; Nomura, Kazunori; Kamiya, Yuichi*; Asanuma, Noriko*; Matsuura, Haruaki*; et al.

Progress in Nuclear Energy, 117, p.103090_1 - 103090_8, 2019/11

https://doi.org/10.1016/j.pnucene.2019.103090

Analysis of the radioactivity concentrations in low-level radioactive waste generated from JRR-2 and JRR-3 facilities

Haraga, Tomoko; Shimomura, Yusuke; Mitsukai, Akina; Ishimori, Kenichiro; Kameo, Yutaka

JAEA-Data/Code 2019-004, 48 Pages, 2019/10

JAEA-Data-Code-2019-004.pdf:4.67MB

In the future, radioactive wastes which generated from research and testing reactors in Japan Atomic Energy Agency are planning to be buried for the near surface disposal. Therefore, it is required to establish the method to evaluate the radioactivity concentrations of radioactive wastes by the time it starts disposal. In order to contribute to this work, we collected and analyzed the samples generated from JRR-2 and JRR-3. In this report, we summarized the radioactivity concentrations of 19 radionuclides (H, C, Cl, Co, Ni, Sr, Nb, Tc, Ag, I, Cs, Eu, Eu, U, U, Pu, Pu, Am, Cm) which were obtained from radiochemical analysis of those samples.

Intense chemical weathering in southwest Japan during the Pliocene warm period

Hatano, Nozomi*; Yoshida, Koki*; Adachi, Yoshiko*; Sasao, Eiji

Journal of Asian Earth Sciences, 184, p.103971_1 - 103971_13, 2019/10

https://doi.org/10.1016/j.jseaes.2019.103971

Whole rock major and REE geochemistry and mineral compositions of the Pliocene sediments in southwest Japan reveal the effects of source rock compositions and grain sizes, as well as the relationship between sedimentary environments and the degree of chemical weathering in the Pliocene warm period. A wide variation in the degree of chemical weathering, source rock compositions and grain sizes were observed with vertical and spatial changes in the sedimentary environment. Regardless of the wide variety of source rock compositions and grain sizes, REE and kaolinite-rich clay mineral concentrations in sediments, of which CIA values are generally above 90, are indicative of the intense weathering conditions that prevailed in the Pliocene period (3-4 Ma) in southwest Japan.

Research plan on geosphere stability for long-term isolation of radioactive waste (Scientific program for fiscal year 2019)

Ishimaru, Tsuneari; Ogata, Nobuhisa; Hanamuro, Takahiro; Shimada, Akiomi; Kokubu, Yoko; Asamori, Koichi; Niwa, Masakazu; Shimada, Koji; Watanabe, Takahiro; Sueoka, Shigeru; et al.

JAEA-Review 2019-010, 46 Pages, 2019/09

JAEA-Review-2019-010.pdf:2.45MB

This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of high-level radioactive waste (HLW) in Japan Atomic Energy Agency, in fiscal year 2019. The objectives and contents in fiscal year 2019 are described in detail based on the outline of 7 years plan (fiscal years 2015-2021). Background of this research is clarified with the necessity and the significance for site investigation and safety assessment, and the past progress in this report. In addition, the plan framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.

Hydraulic tests using borehole PB-V01 in the Horonobe Underground Research Project

Samata, Yoichi; Iwata, Tatsuya*; Ishii, Eiichi

JAEA-Data/Code 2019-008, 19 Pages, 2019/09

JAEA-Data-Code-2019-008.pdf:2.82MB
JAEA-Data-Code-2019-008-appendix(CD-ROM).zip:1.38MB

In Horonobe Underground Research Laboratory Project, hydraulic tests for the excavation damaged zone have been performed in order to characterize the hydrological properties of the zone. In PB-V01 borehole, pore pressure observation started in October 2008, but the pore pressure is currently reduced by about 3 MPa compared to that time. In this report, in order to evaluate the influence that this pore pressure drop has on the permeability of the rock, the results of the in-situ permeability test using the long-term hydraulic pressure monitoring device installed in the same hole are summarized.

Diagrams for finite strain equations and rough estimation of shear strain

Shimada, Koji

Chishitsu Gijutsu, (9), p.25 - 40, 2019/09

Today many collaborations are there in Earth-scientific research and development. Structural geology can serve crucial information on tectonic strain at sampling point in Japan, belonging to the circum-Pacific orogenic belt. Visualize of strain estimation would be effective during field geological survey and for better understanding for non-specialist on structural geology. Illustrations decoding mathematical expressions of strain estimation methods are presented here.

Characterizing the permeability of drillhole core samples of Toki granite, central Japan to identify factors influencing rock-matrix permeability

Kubo, Taiki*; Matsuda, Norihiro*; Kashiwaya, Koki*; Koike, Katsuaki*; Ishibashi, Masayuki; Tsuruta, Tadahiko; Matsuoka, Toshiyuki; Sasao, Eiji; Lanyon, G. W.*

Engineering Geology, 259, p.105163_1 - 105163_15, 2019/09

https://doi.org/10.1016/j.enggeo.2019.105163

Rock matrix permeability is mainly controlled by microcracks. This study aims to identify the factors influencing the permeability of the Toki granite, central Japan. Permeability of core samples, measured by a gas permeameter, largely increases in the fault and fracture zones. Although a significant correlation is identified between permeability and P-wave velocity, this correlation is enhanced by classifying the samples into two groups by the Mn/Fe concentration ratio. Thus, lithofacies is another control factor for permeability due to the difference in mineral composition. Moreover, permeability shows significant negative and positive correlations with Si and Ca concentrations, respectively. These concentrations are probably affected by dissolution of silicate minerals and calcite generation in the hydrothermal alteration process. Therefore, a combination of hydrothermal alteration and strong faulting are the predominant processes for controlling permeability.

Hydration and degradation of High content Fly ash Silica fume Cement (HFSC)

Anraku, Sotaro; Walker, C.*; Oda, Chie; Mihara, Morihiro; Honda, Akira

Proceedings of 15th International Congress on the Chemistry of Cement (ICCC 2019) (Internet), 11 Pages, 2019/09

Development of phosphate modified CAC cementitious systems with reduced water content for the immobilization of radioactive wastes

Garcia-Lodeiro, I.*; Irisawa, Keita; Meguro, Yoshihiro; Kinoshita, Hajime*

Proceedings of 15th International Congress on the Chemistry of Cement (ICCC 2019) (Internet), 10 Pages, 2019/09

The immobilization of low or intermediate-level radioactive wastes in cements is a common practise. Grout, a mixture of Portland cement and supplemental cementitious materials, is commonly used to encapsulate the wastes. However, the conventional cementing process based on portland cement has the risk of hydrogen gas generation, due to the radiolysis of the water intrinsically present in the cement matrix both in the pore solution and the hydrated products. The addition of phosphates to calcium aluminate cement (CAC) is interesting because this system sets and hardens via the acid-based reaction, between the acid phosphate solution and the basic CAC cement. Due to this different mechanism of reaction, it would be possible to generate a solid cementitious product with a reduced water content, which can be beneficial to minimize the risk of hydrogen gas generation associated with the radiolysis of water by radioactive wastes. The present study investigates the effect of water reduction on a phosphate modified CAC systems at different temperatures (35C, 60C, 95C, 110C,180C) in the initial 7 days of curing. Experimental results indicate that these phosphate-based cements do not form the conventional CAC crystalline hydration products in the condition tested, but provide a structural integrity despite a significant amount of water loss. The results also suggest the formation of hydroxyapatite in samples cured at 95C.